Preheat oven to 180°C. Grease and line a baking dish (30 x 20 cm) with baking paper and set aside.
Place the butter in the mixing bowl and melt for 2 minutes / 50°C / speed 1, or until the butter is completely melted.
Add the flour, baking powder, sugar, and desiccated coconut, then mix for 10 seconds / speed 4. Scrape down the sides of the bowl with a spatula, then mix again for another 10 seconds / speed 4. Transfer the mixture into the prepared tin and press it down to form the base.
Bake for 10 minutes (180°C). Let the base cool in the tin for approximately 1 hour. Clean and dry the mixing bowl.
Place the condensed milk and butter in the mixing bowl and cook for 20 minutes / 100°C / speed 3.
Pour the caramel mixture over the cooled base in the tin, then bake for another 10 minutes (180°C) and set aside. Clean and dry the mixing bowl.
Place the chocolate in the mixing bowl and grate for 5 seconds / speed 8. Scrape down the sides of the bowl with a spatula.
Add the butter and melt for 2 minutes and 30 seconds / 50°C / speed 2, or until the butter and chocolate are completely melted.
Pour the chocolate mixture over the caramel layer and let it cool. Refrigerate for about 1 hour or until set. Once set, slice and serve.